Westport Water Supply S Griffin Public Meeting March 14 th 2013
Outline of presentation • Brief history of water supply • Issues of recent times • Asset management of existing supply and reticulation • S trategic Review of Water S upply • Final Options from the peer review • Treatment Plant Upgrade – Opus • Costs
Purpose of the upgrade • To provide a safe and secure water supply for Westport for the next 50 to 100 years • To restore consumer confidence with a water supply that has no taste and odours • A water supply that meets the Drinking water standards
History • Water supply constructed 1903 • Water Treatment plant constructed 1985 • Maj or Upgrade to commence 2013/ 14
• Tunnel collapse in 2000 resulted in first strategic investigation • Connell Wagner engaged to look at all aspects of existing supply and also other potential sources • Risk of tunnel collapse was quantified – outcome was the construction of alternative pump supply – cost about $1m • Water pumped from lower reaches of Orowaiti introduced algae to reservoirs – a possible source of the taste and odour
• Further tunnel collapse resulted tunnel being piped $600,000 • Backwash failure resulted in the residual reservoir material being piped into the town reticulation. • S econd occurrence almost 12 months later
Main Replacements • Main trunkmain varies in age • To replace a 454mm pipe means minimal water or to some residents none at all 2003/ 04 - 10 pipes 2004/ 05 – 5 pipes 2005/ 06 – 6 pipes 2006/ 07 – 5 pipes 2007/ 08 – 7 pipes 2008/ 09 – 1 pipe 2010/ 11 – 11 pipes 2011/ 12 – 2 pipes To some consumers these breaks occur too often.
Reticulation &Pressure • Like the trunk main the reticulation varies with age and material • Operates at high pressure • Westport uses about twice as much water per capita than the average • Combination of leakage and pressure. • Upgrade will address pressure and possibly the replacement of the trunk main but not the reticulation.
Proposed Upgrade • Council have revisited the Connell Wagner strategic review • Peer reviewed by Opus • In addition to peer reviewing the options to upgrade an operational review was undertaken of the management of the treatment plant process • The review by Opus came back with three options • Infiltration gallery/ bore field Buller River at Te Kuha • Infiltration gallery/ bore field Buller River at Nine Mile (Reedys) • Existing supply upgraded
Proposed Upgrade • Council decision to upgrade the existing water supply rather than construct from different source. • Decision was based on economics and also sustainability. • Proposed upgrade starts at the source and reviews or renews every component progressively to the start of the reticulation
Asset Management • Council has a GIS based asset management data base • This is still in a development stage replacing a paper inventory • Reticulation is plotted with material type and age • Condition rating is an on going aspect and is evaluated at time of repairs.
Management Asset
Management Asset
Management Asset
Westport Water Treatm ent Plant Upgrade
Introduction • Westport drinking-water supply – A unique supply with unusual features • Why is an upgrade needed? • What will the upgrade consist of?
Westport Supply
Westport Supply
Westport Supply
Westport Supply
Westport Supply
Existing system Coagulant Chlorine Lime Giles Creek Raw water ponds Filters Westport Treated water x3 x2 storage reservoir Backwash water from reservoir Orowaiti River Backwash water To waste
Why is an upgrade needed? • There have been some problems with water quality from the treatment plant • We know a lot more about water supply contaminants than we did in 1986 • Water treatment technology has improved considerably • Legislation introduced in 2007 • Drinking water standards
Raw water ponds bypass Coagulant Chlorine Lime Raw water ponds bypass Giles Creek Raw water ponds Filters Westport Treated water x3 x2 storage reservoir Backwash water from reservoir Orowaiti River Backwash water To waste
Raw water ponds by-pass
Turbidim eter Coagulant Chlorine Lime Raw water ponds bypass Turbidity meter Giles Creek Raw water ponds T Filters Westport Treated water x3 x2 storage reservoir Backwash water from reservoir Orowaiti River Backwash water To waste
Flocculation tanks Coagulant Chlorine Lime Raw water ponds bypass Flocculation tanks Turbidity meter Giles Creek Raw water ponds T Filters Westport Treated water x3 x2 storage reservoir Backwash water from reservoir Orowaiti River Backwash water To waste
Powdered carbon Coagulant Chlorine Lime Powdered carbon Raw water ponds bypass Flocculation tanks Turbidity meter Giles Creek Raw water ponds T Filters Westport Treated water x3 x2 storage reservoir Backwash water from reservoir Orowaiti River Backwash water To waste
Filter backwash storage Coagulant Chlorine Lime Powdered carbon Raw water ponds bypass Flocculation tanks Turbidity meter Giles Creek Raw water ponds T Filters Westport Treated water x3 x2 storage reservoir New backwash tank using water Orowaiti River that is not pH adjusted Backwash water To waste
UV disinfection Coagulant Chlorine Lime Powdered carbon Raw water ponds bypass Flocculation tanks UV disinfection Turbidity meter Giles Creek Raw water ponds T Filters Westport Treated water x3 x2 storage reservoir New backwash tank using water Orowaiti River that is not pH adjusted Backwash water To waste
New treated water storage reservoir Coagulant Chlorine Lime Powdered carbon Raw water ponds bypass Flocculation tanks UV disinfection Turbidity meter Giles Creek Raw water ponds T Filters Westport x3 New treated water x2 storage reservoir New backwash tank using water Orowaiti River that is not pH adjusted Backwash water To waste
Filter to waste and pressure m anagem ent Coagulant Chlorine Lime Powdered carbon Raw water ponds bypass Flocculation tanks UV disinfection Turbidity meter Giles Creek Raw water ponds T P Filters Westport x3 New treated water x2 storage reservoir New backwash tank using water Orowaiti River that is not pH Pressure management adjusted Filter to waste Backwash water To waste
Upgrade consists of • Raw water pond bypass • Flocculation tanks • Powdered carbon • Backwash storage • UV disinfection • New treated water storage reservoir • Filter to waste and pressure management
Tim efram es • Detailed design completed April 2013 • Tenders evaluated June 2013 • Construction begins September 2013 • Bulk of works completed September 2014
S taged upgrade included in Long Term Plan $26,700 Planning, legal & property 2016/ 17 $1,350,000 Enlarge raw water ponds Raw water quality 2018/ 19 $1,500,000 Pipe rest of tunnels $130,000 management 2012/ 13 2020/ 21 $2,887,000 Replace trunk main $700,000 Flocculation tanks Construct treated water 2022/ 23 $2,400,000 $856,700 reservoirs Filter refurbishment $610,000 Line raw water reservoirs $521,000 S eismic strengthen $11,951,200 Cost estimated in 2012 $ Filtered water back wash 2023/ 24 Cost in LTP adj usted for $260,000 2013/ 14 $14,670,329 storage inflation (BERL Factors) $170,000 Filter to waste system $2,719,129 Inflation $951,000 New plant building $413,000 monitoring & control $393,500 UV disinfection & buildings 2014/ 15 Alkalinity correction $215,000 system $375,000 By Pass raw water ponds $1,396,500
Financial Impact Three options: 1.Full upgrade at a cost of $10.3 million defers tunnel piping & lining raw water reservoirs. 2.Part upgrade at a cost of $8.9 million as above but also defers cleaning ot raw water reservoirs 3.Minimum upgrade at a cost of $5.8 million as above but also defers replacing trunk main.
Upgrade Expense Comparison
Effect on Westport Targeted Rates
Effect on Westport Targeted Rates Westport Targeted Rates (GS T Exclusive) 2014 2015 2016 2017 2018 2019 2020 2021 2022 Full Upgrade $580 $720 $790 $850 $870 $890 $900 $900 $910 Part Upgrade $580 $710 $760 $800 $820 $840 $860 $870 $880 Minimum Upgrade $580 $690 $720 $740 $740 $750 $760 $780 $790
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